PP- Antiprotozoal drugs

Question 1

What are the main protozoan infections in humans?

Answer 1

• malaria
• amoebiasis
• pneumocystis infection
• trypanosomiasis
• leishmanisasis

Question 2

What is malaria?

Answer 2

• it is a mosquito-borne disease caused by various Plasmodium species
• a major killer in the developing world

Question 3

Which Plasmodium species cause most of the mortality of the malaria patients?

Answer 3

Plasmodium falciparum

Question 4

Who ar ein the risk group of Plasmodium falciparum ?

Answer 4

the greatest risk, for children under 5 years of age and to all non-immune individuals

Question 5

How are the parasite that cause malaria transmitted to humans?

Answer 5

the parasites (Plasmodium) are transmitted to humans by the bite of infected female Anopheles mosquito vector

Question 6

Which Plasmodium species cause malaria?

Answer 6

• P. falciparum
• P. vivax
• P. ovale
• P. malariae

Question 7

How are antimalarials categorized?

Answer 7

according to the stage of the parasite that they affect

Question 8

P. vivax

Answer 8

gives rise to hypnozoites in the liver; these lie dormant and can produce relapses months or years later

Question 9

P. falciparum

Answer 9

does not form hypnozoites and thus has no exo-erythrocytic stage

Question 10

P. malariae

Answer 10

• is rare

- has a 72-h cycle (quartan malaria) and also has no exo-erythrocytic stage

Question 11

What does chloroquine do?

Answer 11

reduces the necessary digestion of haemoglobin by the plasmodium by inhibiting the parasite´s haem polymerase

Question 12

What is haem polymerase?

Answer 12

it is the enzyme that inactivates the toxic free heam generated by the plasmodium

Question 13

How is chloroquine given?

Answer 13

• usually orally (half-life 0.5h)

- injection

Question 14

How is chloroquine distributed?

Answer 14

it is widely distributed in the body but much is concentrated in the parasite cells

Question 15

What are the unwanted effects of chloroquine?

Answer 15

• nausea
• vomiting
• dizziness
• large doses can cause retinopathy and bolus injections can cause dysrythmias

Question 16

Which species of Plasmodium are resistant to chloroquine?

Answer 16

• P. falciparum is resistant in most parts of the world

- P. vivax is resistant i some places

Question 17

Schizonticide def:

Answer 17

an agent selectively destructive of the schizont of a sporozoan parasite

Question 18

What does the blood schizonticide act on?

Answer 18

they act on the asexual erythrocytic stage to interrupt schizogony and thus terminate clinical attacs

Question 19

How are blood schizonticide divided?

Answer 19

1. rapid-acting blood schizonticide

2. slow-acting blood schizonticide

Question 20

Give examples of rapid-acting blood schizonticide?

Answer 20

• quinine
• chloroquine
• mefloquine

Question 21

Give examples of slow-acting blood schizonticide?

Answer 21

• sulfonamide

- pyrimethamine

Question 22

How is halofantrine given?

Answer 22

• orally (half-life 30 days)

- the parent drug have a half-life of 1-2 days and the active metabolite 3-5 days

Question 23

What are the unwanted effects of using halofantrine?

Answer 23

• GI tract disturbances

- occasionally cardiac dysrhythmias

Question 24

How is mefloquine given?

Answer 24

• orally (half-life 30 days)

- slow onset of action

Question 25

How does the mefloquine work?

Answer 25

like, chloroquine, it inhibits haem polymerase

Question 26

What are the unwanted effects of using mefloquine?

Answer 26

- GI tract disturbances | - may produce neuropsyciatric symptoms

Question 27

How is quinine given?

Answer 27

- orally (half-life 10h) | - can be given by IV infusion

Question 28

What is quinine used with?

Answer 28

- doxycycline and either * dapsone (given orally, half life 24-48h) * sulfadoxine, a long-acting sulfonamide (half-life 8 days)

Question 29

What are the unwanted effects of using quinine?

Answer 29

- GI upset - tinnitus - headache - blurred vision - allergic reaction - large doses affect the heart (dysrythmias) and/ or the CNS (delirium)

Question 30

What is pyrimethamine?

Answer 30

a folate antagonist

Question 31

What does the pyrimethamine do?

Answer 31

inhibits folate utilization having greater affinity for the plasmodial than for the mammalian system

Question 32

What is pyrimethamine used with?

Answer 32

- sulfadoxine, slow-acting (half-life 4 days). It has few unwanted effects

Question 33

Proguanil:

Answer 33

- similar action of pyrimethamine | - slow-acting schizonticide (half-life 16h) with some action on the pre-erythrocytic stage of P. vivax

Question 34

How is proguanil given?

Answer 34

given orally

Question 35

How is primaquine given?

Answer 35

- orally | - half-life 3-6h

Question 36

What is primaquine usually given with?

Answer 36

chloroquine

Question 37

What are the unwanted effects of primaquine?

Answer 37

it can cause hemolysis in individuals with genetic deficiency of red cell glucose 6-phosphate dehydrogenase

Question 38

What is doxycycline?

Answer 38

- broad-spectrum tetracycline antibiotic | - acts by inhibiting plasmodial protein synthesis

Question 39

What is artemether?

Answer 39

a semi-synthetic derivative of artemisin

Question 40

What is artemether?

Answer 40

a compound extracted from a shrub used in traditional Chinese medicine

Question 41

How is artemether given?

Answer 41

- orally - rectally - IM

Question 42

artemether mechanism of action:

Answer 42

- concentrated in parasitic cells where it generates reactive oxygen species; and may inhibit a calcium transporter - inhibits hemoglobin degradation in the parasite

Question 43

When is artemether used?

Answer 43

in combination therapy only!

Question 44

What are the unwanted effects of artemether?

Answer 44

neurotoxicity can occur with high doses

Question 45

What causes amoebiasis?

Answer 45

ingestion of the cysts of Entamoeba histolytica

Question 46

How does the cysts of Entamoeba histolytica develop in the body?

Answer 46

the cyst develop in the GI tract into motile trophozoites which can invade the intestinal wall